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Plasmid content, auxotype and protein-I serovar of gonococci isolated in the Gambia
A P Johnson1, D Abeck, R A Wall
1Division of Sexually Transmitted Diseases, MRC Clinical Research Centre, Harrow, Middlesex.
Abstract:
Twenty-nine strains of penicillinase-producing Neisseria gonorrhoeae (PPNG) and 30 non-penicillinase-producing strains, all isolated in the Gambia, were characterized in terms of their plasmid content, auxotype and protein-I serovar. Sixty-two per cent of the PPNG strains contained the 3.2 MDa penicillinase-coding plasmid, and 38% had the 4.4 MDa plasmid. All the PPNG strains contained the 2.6 MDa cryptic plasmid but lacked the 24.4 MDa conjugative plasmid. In contrast, 46.7% of the non-PPNG strains harboured only the cryptic plasmid while 16.7% contained both the cryptic and conjugative plasmids. Seventeen per cent of the non-PPNG strains contained the conjugative plasmid only and 20% lacked plasmids. The PPNG and non-PPNG strains also differed in terms of their protein-I serovar. Eighty-six per cent of the PPNG strains belonged to serogroup 1 A, whereas the majority (60%) of non-PPNG strains belonged to serogroup 1 B. There was no significant difference in the auxotypes of the PPNG and non-PPNG strains, with both groups consisting predominantly of prototrophic and proline-requiring strains, with a minority of strains requiring arginine. When the 59 strains were each characterized in terms of their combined plasmid profile, auxotype and serovar, 39 different combinations were noted, which indicates the heterogeneous nature of the gonococcal population found in the Gambia.
Insights
Penicillinase-producing Neisseria gonorrhoeae (PPNG) strains in The Gambia primarily possess specific plasmids and belong to serogroup 1A. Non-PPNG strains exhibit more diverse plasmid profiles and serogroups, indicating a heterogeneous gonococcal population.
Area of Science:
- Microbiology
- Genetics
- Epidemiology
Background:
- Neisseria gonorrhoeae is a significant cause of sexually transmitted infections.
- The emergence of antibiotic resistance, particularly penicillinase-producing Neisseria gonorrhoeae (PPNG), poses a global health threat.
- Understanding the genetic diversity of gonococcal strains is crucial for effective disease control.
Purpose of the Study:
- To characterize penicillinase-producing Neisseria gonorrhoeae (PPNG) and non-penicillinase-producing Neisseria gonorrhoeae strains isolated in The Gambia.
- To analyze plasmid content, auxotype, and protein-I serovar of these strains.
- To assess the genetic heterogeneity of the gonococcal population in the region.
Main Methods:
- Plasmid profiling using molecular techniques.
- Auxotyping to determine nutritional requirements.
- Serotyping based on protein-I variations.
- Comparative analysis of PPNG and non-PPNG strains.
Main Results:
- Sixty-two percent of PPNG strains carried the 3.2 MDa penicillinase plasmid; 38% had the 4.4 MDa plasmid. All PPNG strains possessed the 2.6 MDa cryptic plasmid but lacked the 24.4 MDa conjugative plasmid.
- Non-PPNG strains showed varied plasmid carriage: 46.7% had only the cryptic plasmid, 16.7% had both cryptic and conjugative plasmids, 17% had only the conjugative plasmid, and 20% lacked plasmids.
- Eighty-six percent of PPNG strains were serogroup 1A, while 60% of non-PPNG strains were serogroup 1B. Auxotypes did not significantly differ between PPNG and non-PPNG groups.
- A total of 39 distinct combinations of plasmid profile, auxotype, and serovar were observed among the 59 strains.
Conclusions:
- Significant differences exist in plasmid content and protein-I serovar between PPNG and non-PPNG strains of Neisseria gonorrhoeae in The Gambia.
- The gonococcal population in The Gambia is highly heterogeneous, characterized by diverse combinations of genetic markers.
- These findings highlight the importance of ongoing surveillance and characterization of Neisseria gonorrhoeae strains to monitor antimicrobial resistance and population dynamics.